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Geothermal Installation is Educational Process for Contractors, College

by Tyler Henning

At St. Clair County Community College (SC4) in Port Huron, Mich., contractors and college students alike are learning about green buildings and technologies. The lessons are being taught in unlikely places — in a parking lot and through the passing around of viral videos.

Students at the college will participate in lessons on green environments stemming from a geothermal installation underneath a large parking lot on campus. The parking lot is also outfitted with bioswales and rain gardens to cleanse rainwater before it reaches nearby waterways.

Viral videos are often associated with comedic advertisements, embarrassing moments or other entertaining moments. In the case of SC4's geothermal installation, viral videos provided the education to perform a job in a better way.

In the summer of 2010, construction was completed on a geothermal system for the college's North Building. The building, originally constructed in 1920, was served by two boiler systems, with one of those boilers systems targeted for replacement. The second, remaining boiler continues to serve locker rooms and a gymnasium.

After assembly, we rolled the coil up into a ball that resembled a 'big foot' truck tire and tied it off with rope

David Dahnke

According to local newspaper reports, SC4 will save an estimated $52,000 per year for the North Building's HVAC. That cost savings is based on the system reaching 30 percent savings on energy use over the preexisting chiller and boiler system.

"The North Building is comprised of a 30,000-square-foot, two-story classroom building with an adjacent 24,600-square-foot upper level gymnasium and lower level locker room, complete with support classrooms and weight rooms," said Ron Chapdelaine, project designer for Peter Basso Associates Inc. "The existing system had a heat exchanger off of the existing boiler system and a cooling tower for the cooling side of the existing water-to-air heat pump system. We looked at putting back similar equipment, but with the parking lots slated for replacement, it made sense to use a closed loop ground source geothermal system.

"The designed geothermal system was based on a nominal 200-ton system horizontal slinky field system located under the renovated parking lot. The air-handle system selected for the building are plate-and-frame heat exchanger recovery units, roof-mounted with chilled water cooling coils and hot water heating coils capable of 100-percent economizer mode of operation. The indoor units are variable air volume (VAV) boxes with hot water re-heater coils within each room and CO2 sensors to monitor building occupancy outside air demand ventilation control."

Chapdelaine and Peter Basso Associates recommended a water-to-water heat pump manufactured by ClimaCool®, a roof-mounted energy recovery unit made by Innovent, VAV boxes from Price and pumps from Bell and Gossett.

Normally, vertical wells would suffice for a geothermal project in Michigan, but the presence of a methane field forced another approach.

"We originally looked at a vertical well system, but due to methane gas pressures at around 30 PSIG only 50 feet below the ground in the city of Port Huron, it would not allow for a vertical well system," said Chapdelaine.

Three fields were dug out by Sopha Underground Maintenance to a depth of 8 feet, 6 inches, with each 615 feet long and 60 feet wide. In the three excavated pits, a total of more than 30 miles of piping were used to construct the slinky loops.

Not a stranger to geothermal piping installations, local contractor Watson Brothers sought more information on installing a horizontal slinky system and boosting productivity on the project. A consultation with Etna Supply, the project's pipe and fusion machine supplier, led to the sharing of a YouTube link. The link clued Watson Brothers into a smarter way for moving and packaging the 1-inch IPS high-density polyethylene (HDPE) coiled pipe for delivery to the job site in a manner that would ease installation.

Watson Brothers personnel watched the video, taking notes and then set forth to replicate the process. In the shop, workers set up a rig with 4-foot-wide-by-8-foot-long pieces of plywood with 2-inch-by-4-inch pieces of wood attached at a 3-foot distance stretching the length of the rig. Together, the lengths of plywood were 45-feet long. The 1-inch HDPE coil was delivered in 500-foot coils.

The coil was designed to have a 10-inch overlap when unrolled on site, so corresponding10-inch increments were marked off on the plywood. Workers unraveled the coil on the plywood, recoiling the loops to be 3 feet wide. Once in place, the coils were zip-tied to stay in place.

"After assembly, we rolled the coil up into a ball that resembled a 'big foot' truck tire and tied it off with rope," said David Dahnke, project manager for Watson Brothers. "This allowed us to roll the coil down into the field, cut the rope and unroll the slinky into place."

The technique allowed Watson Brothers to haul six coil bundles to the site on a flatbed truck.

The headers required for the slinky field were another critical component. Etna Supply's Troy Taylor fabricated the headers at Etna's Wixom, Mich., location. Taylor fabricated 198 4-by-1-inch and 240 3-by-1-inch sidewall tees on the HDPE headers. The lengths of headers fused by Taylor were trucked to the site, sometimes on a daily basis.

For connecting the loops to the headers, Taylor recommended a new product — McElroy's Socket Fusion Tooling Kit. The kit features a Multi-Mc® heater with microprocessor control and a dial thermometer to monitor heater temperature. "Our guys like having the ability to dictate what the temperature of the heater is," said Dahnke. "Our other socket tooling equipment didn't afford us that luxury."

By using a kit, Watson Brothers were provided heater adapters and tools specific to the size ranges commonly associated with geothermal installations. All of the components fit into a custom-sized toolbox.

The project at SC4 was completed by August 23rd, the first day of the fall semester. The cost of the geothermal system, resurfacing of the parking lots, construction of bioswales and rain gardens, and resurfacing of another parking lot on campus was $4.3 million. The projects were funded by the school's millage income.

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